(1) Field of the Invention
The present invention relates to low heat generation type rubber compositions.
(2) Related Art Statement
In order to cope with social demands for natural resource saving and energy saving, development of low fuel consumption tires has strenuously been made for several years in the rubber industries, particularly in the tire industry. The development of such low fuel consumption tires indispensably requires low heat generation type rubber compositions. For instance, Japanese patent application Laid-open Nos. 57-51,503, 57-55,204, and 58-36,705 describe techniques for using styrene-butadiene rubber (SBR) in which contents of bound styrene and vinyl bonds are controlled. However, those techniques could not be applied to rubbers other than SBR. Particularly, they could not be applied at all to natural rubber most widely used in heavy duty pneumatic tires.
On the other hand, Japanese Patent publication No. 50-38,131, British Pat. No. 1,185,896, U.S. Pat. No. 2,315,885, U.S. Pat. No. 2,315,856, etc. describe that heat generation characteristic of rubber compositions is improved by adding nitrosoquinolines, nitrosoanilines, etc. thereto.
However, such nitroso compounds indeed improve heat generation characteristic, but there is a problem in that particularly when they are applied in case of polyisoprene rubber, wear resistance of the rubber compositions is greatly deteriorated due to great peptizing action. Further, when the above nitroso compounds are applied in case of polyisoprene rubber, heat generation characteristic is conspicuously improved. On the other hand, when they are applied to synthetic rubbers such as styrene-butadiene copolymer rubber or polybutadiene rubber, great heat generation characteristic-improving effect cannot be expected.